Our primary objective continues to try to identify the effects of chronic exposure of human populations to low levels of air pollutants, specifically sulfur compounds and suspended particulates. A follow-up survey has been done in Berlin, N.H. in 1973 on the populations studied in 1961 and 1967. The results of that survey have been coded and are being processed in the computer. The levels of air pollution have been monitored by the state and the city and the results have been made available to us. In addition, we are continuing random monitoring of air pollution using our suit-case sampler for weekly intervals at different seasons of the year. These data will give us more information as to other air pollutants such as oxides of nitrogen, carbon monoxide, hydrocarbons, and when we have an adequate method, sulfates. We also have a number of hi-vol samples obtained in 1965-1967 that we plan to analyze for sulfates when we have an appropriate method.